How to set a dead man's switch for Bitcoin

Hi, if I want my heir to be able to access my seed phrase after my death, but I don't want them to know my seed phrase now, how can I best go about setting this up?

For example one idea is to put the seed phrase in a physical safe in a bank, and after I die, the heir should be able to access the safe and look at the piece of paper in it.

But is there any easier / more effective way to do it?

Thanks a lot!